SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afc818bfb58568cb8fb4f6111fdbffdf4a489ed69b77f1ddd8b28feb4aab42f8' 
  AND token = 'mr7dQ89cSI2/LW11hmd6zmFGpzBGirdX5lFmejgXIZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}